Artificial knee joint



13, 1940- H. SIMONSISON 2,211,298

ARTIFICIAL KNEE JOINTS Filed April 2, 1938 INVENTOR:

Patented Aug. 13, 1940 UNITED STATES PATENT OFFICE Application April 2, 1938, Serial No. 199,590 In Sweden April 10, 1937 2 Claims.

The invention herein considered consists of a kneejoint for artificial legs, that lengthens and contracts and sometimes stops the bending of the knee during the walking, thus making the walk 5 less tiring and unsteady for the user.

The kneejoint is shown from the side in Figs. 1 and 3 of the enclosed drawing. Figure 1 shows the leg in its lengthened position. Figure 2 shows a front vertical section of the joint. Figure 3 shows the leg at the beginning of the step when the joint is unloaded and the leg contracted.

In the drawing, I indicates the leg above the knee (the thigh section) and 2 the leg below the knee (the shin section). The leg below the knee 5 2 is connected with the leg above the knee l through a double link 3, 6. The link 3 is rotatably connected to the leg below the knee by a transverse bolt 4, whilst a transverse bolt 5 rotatably connects the link 3 with the link 6, which through a transverse bolt 1 is rotatably connected to the leg above the knee I. The bolts 4, 5 and l are arranged in bearings preferably ball bearings, '8 indicates a recess or space in the thigh section, 9 indicates a stopping surface for the bolt 5 in the lower part of the recess or space, H] a stopping surface for said bolt in the upper part of the space, H is a stopping surface in the hind part of the leg above the knee, 12 a stopping surface in the front part of the leg above the knee, 13 a 30 stopping surface in the hind part of the leg above the knee and M a stopping surface in the front part of the leg below the knee.

The bearings 4, 5 and 1 are so arranged that they can move peripherically in relation to each other whereby the motion of the bearing 5 around the bearing 4 takes place at the first moment of the discharge of the step when the leg above the knee is advanced relative to the leg below the knee. By this motion the surfaces l2 and H are caused to slide forward off the surfaces l4 and i3 respectively, whereby the length of the leg is decreased as shown in Figure 3, and furthermore it is made possible to bend the leg. At the second moment of the step when the leg is carried forward, the upper and the lower parts of the leg are receding from one another. Hereby the leg is so much extended as is permitted by the stopping surface 9 in the space 8 or recess. At the same time the leg below the knee is projected forward in relation to the leg above the knee, the joint being thus checked when the supporting surfaces l2, l4 and H, 13 come into contact with each other and thus the leg is prevented from bending, when the weight of the'body is carried over to it. (See Fig. 1.)

The design of the joint shown in the drawing is only one form of construction of the present invention. The mentioned details may mechanically be connected in any other suitable way. The bearing 5 and the stopping parts for it may also be arranged in the shank section of the leg.

The characteristic feature of the invention is that the leg above the knee (thigh) is rotatably connected with the leg below the knee (shin) by one or plural double links that cooperate parallelly, the links being rotatably attached around If a centre fixed to the leg above the knee and like- 0 wise rotatably attached around a centre fixed to the leg below the knee and further by a bolt connecting the links, the links being so arranged that they at different movements and moments of the walk permit the leg to shorten and lengthen, and further that when the leg below the knee is loaded the leg is prevented from bending in angle to the leg above the knee by properly arranged stopping surfaces.

I do not wish to be limited as to details of construction. These may be modified in several respects without departing from the spirit of my invention.

I claim:

1. Knee joint for artificial legs, comprising a pair of links rotatably connected to the thigh section of the leg just above the knee, and another pair of links rotatably connected to the shin section of the leg just below the knee, said two pairs of links forming an angle with each other and being, in the angle point, rotatably connected to each other by means of a bolt, a stop in the thigh section of the leg for limiting the downward movement of said bolt, and supporting and stopping surfaces on the thigh section and on the shin section of the leg, located in front of and behind the centre line of the knee joint, said surfaces being in contact with each other in the lengthened position of the leg.

2. Knee joint according to claim 1, characterised in that a stop is arranged in the thigh section of the leg for limiting the upward movement of the angle point bolt.

LUDVIG HJALMAR SIMON SSON. 

